The case would have been difficult to prosecute even with the woman's cooperation because of the nature of the allegations, Mahoney said. But without the woman, the state essentially has no case, she said.

Judge Joan Alexander agreed to nolle, or not prosecute, the charges.

Boyce, 48, of Blue Hills Avenue, had been charged with first-degree sexual assault, first-degree unlawful restraint and second-degree making a false statement.

Police were called to Boyce's home on the morning of May 11, according to an arrest warrant affidavit. Ambulance personnel had been dispatched to the address after reported that a person had overdosed at the home.

Boyce initially told the medics that no one needed medical attention, the report states, but he allowed officers, then the ambulance workers, in the house after police received a second call for help.

An incoherent woman was lying face up on the basement apartment's concrete floor, police said. She later told police she had been sexually assaulted. She said she asked her mother to send an ambulance to the address in two text messages.

The woman told police she had been smoking crack with Boyce and his girlfriend when Boyce started making advances toward her, the report states. The girlfriend was in and out of the apartment, police said.

The woman told Boyce she didn't want to do anything and he stopped, she told police. But later, after he watched pornographic videos, he grabbed her, shoved her on his bed and sexually assaulted her, holding her down, the report states.

Before Boyce knew of the rape complaint, he told officers that he never had sex with the woman, police said. He eventually said that he had sexual relations with her that morning, but that it was consensual.

Mahoney said her request to drop the charges has nothing to do with the performance of police, whom she said did an excellent job with the investigation.